Use literal instead of computed value in token lookup

genheaderfunc.py

@@ -77,7 +77,7 @@ int lookup_token(const uint8_t *name, size_t namelen) {
         print '''\
   case {}:'''.format(size)
         print '''\
-    switch (name[namelen - 1]) {'''
+    switch (name[{}]) {{'''.format(size - 1)
         for c in sorted(ents.keys()):
             headers = sorted(ents[c])
             print '''\